"Both of them appear to be essential for letting the amputated tissue know what to regenerate" in flatworms, he said.

If flatworms with suppressed B-Catenin are sliced somewhere on its body, "heads will grow ... no matter where you cut." Whatever parts are cut off, "essentially you get heads to grow."

"Ordinarily, the APC gene helps to control the levels of B-Catenin protein to regulate its action," he said. But if the APC is eliminated, B-Catenin protein accumulates in the animal. "So now there's an excess of Beta-Catenin," he said. When flatworms missing the APC gene are cut, "we get tails."

APC and B-Catenin work together in "sort of a seesaw type of relationship."

Even so, how does the flatworm know whether to produce a head or a tail? The team believes molecules outside the cell may initiate the process.

These molecules occur in different levels throughout the body of the flatworm, Sanchez Alvarado thinks. They may form "a functional gradient from the very tip of the head to the very tip of the tail of the animal." The level of this material that interacts with the cell may be a signal telling where on the body the amputation happened, and therefore, what to regrow.

A step toward prompting regeneration in other forms of life may be to look at how these processes interact in animals unable to regenerate.

Knowing where to check, he said, "now we can look ever more closely than we could before."

Will the discovery be useful in regenerating human tissue? Sanchez Alvarado replied, "Although much more research is needed to definitely answer this question, our findings are likely to increase our understanding about regeneration events in animals, including humans."

---

E-mail: bau@desnews.com